code: def test_constructor(self, gpt_model):
      assert isinstance(gpt_model, MegatronGPTModel)
  
      num_weights = gpt_model.num_weights
      assert num_weights == 6702976
  
file_path: NeMo/tests/collections/nlp/test_gpt_model.py
imports: import os
  import pytest
  import torch
  from omegaconf import DictConfig
  from pytorch_lightning import Trainer
  from nemo.collections.common.tokenizers.huggingface.auto_tokenizer import AutoTokenizer
  from nemo.collections.nlp.models.language_modeling.megatron_gpt_model import MegatronGPTModel
  from nemo.collections.nlp.modules.common.megatron.utils import get_ltor_masks_and_position_ids
  from nemo.collections.nlp.parts.nlp_overrides import NLPDDPStrategy
label_desc: Use image node_id 1 for calling the TestGPTModel obj's underlying member method code with example usage: obj.test_constructor(gpt_model) without return types